Update: With the Black Mesa Source website a little traffic-heavy at this point, an official torrent of the game has been released. Pick it up through Dropbox.
Original post: The day has finally arrived - Black Mesa Source is now available for download via the game’s website.
This release allows you to play Black Mesa’s re-envisioning of Half-Life using the Source Engine (completely different to Valve’s own port) all the way up to Lambda Core, giving you around 8-10 hours of gameplay. Away from today’s release, the game is also being prepared for launch on Steam after being ‘Greenlit‘ earlier in the week.
The website is currently under heavy load so it could be a while before you get your hands on it. The download is free and only requires that you have Source SDK Base 2007 installed – thanks to Noface for the correction.